Piston-driven positive displacement pump

ABSTRACT

In an embodiment of the present invention a pump ( 100 ) is disclosed which comprises a head ( 110 ), in which at least a cylinder is fashioned in which a piston ( 105 ) is slidably housed, and a casing ( 145 ) fixed to the head ( 110 ), which defines an internal volume in which a crankshaft ( 150 ) and at least a conrod ( 155 ) are housed, which at least a conrod ( 155 ) connects the crankshaft ( 150 ) with the piston ( 105 ), such as to be able to transform a rotary motion of the crankshaft ( 150 ) into an alternating motion of the piston ( 105 ), signaling means ( 210 ) of the temperature of lubricating oil contained in the internal volume of the casing ( 145 ) being applied to the casing ( 145 ).

FIELD OF THE INVENTION

The present invention relates to a piston-driven positive displacement pump, having a single piston or a plurality thereof.

In particular, the present invention relates to high-pressure pumps such as those which are commonly used in the industrial cleaning sector or other sectors of industry and agriculture.

BACKGROUND

As is known, a high-pressure pump generally comprises a plurality of pistons, each of which is slidably housed internally of a respective cylinder such as to define therewith a variable-volume pumping chamber, which communicates with an aspirating conduit and a delivery conduit via respective valves.

The cylinders and aspirating and delivery conduits are normally realized in a single monolithic body made of a metal material, for example brass, which is commonly known as the head.

The head is fixed to a casing in which a crank shaft and a plurality of conrods are housed, each of which is destined to connect the crank shaft with a respective piston, such as to transform the rotary motion of the former into an alternating motion of the latter.

To prevent malfunctioning, conserving the integrity of the mechanical components and reduce the energetic consumption associated to the functioning of the high-pressure pumps, it is essential that the above-delineated mechanism is constantly lubricated.

The lubrication is generally obtained with an agitated oil-bath system, i.e. by predisposing, in the internal volume of the casing, a predetermined quantity of lubricating oil which strikes the support bearings of the crank shaft and which is agitated by the movement of the crank shaft and the conrods, in such a way as also to reach the connecting joints between the crank shaft and the conrods and the connecting joints between the conrods and the pistons.

A drawback of this solution derives however from the fact that the effectiveness of the lubrication depends on some chemical-physical characteristics of the lubricating oil, such as the viscosity, which can strongly depend on the temperature which the lubricating oil reaches during the functioning of the high-pressure pump.

For this reason, if the temperature of the lubricating oil is too high or too low with respect to an optimal design value, it can happen that the lubrication of a high-pressure pump is defective, causing an increase in wear and energy consumption.

A further drawback consists in the fact that if the temperature of the lubricating oil reaches extremely high values, safety problems can arise, or in any case a permanent deterioration of the chemical-physical characteristics of the lubricating oil can ensue.

At present the temperature of the lubricating oil is not controlled by the users during functioning of the pump, so that the risk of reaching critical conditions or in any case causing malfunctioning is effectively rather high.

SUMMARY

An aim of the present invention is to obviate the mentioned drawbacks, by providing a solution that enables users to intervene in good time in a case in which the temperature of the lubricating oil exhibits anomalous values.

A further aim of the present invention is to attain the above-mentioned objective with a solution that is simple, rational and relatively inexpensive.

These and other aims are attained by the characteristics of the invention as recited in independent claim 1. The dependent claims delineate preferred and/or particularly advantageous aspects of the invention.

In particular, in an embodiment of the present invention a pump is provided comprising a head, in which at least a cylinder is afforded in which a piston is slidably housed, and a casing fixed to the head, which defines an internal volume in which are housed a crankshaft and at least a conrod able to connect the crankshaft with the piston, such as to be able to transform a rotary motion of the crankshaft into an alternating motion of the piston, signaling means of the temperature of the lubricating oil contained in the internal volume of the casing being applied to the casing.

Thanks to this solution, the signaling means enable the users to keep the temperature of the lubricating oil under control during the functioning of the high-pressure pump, placing the users in a condition to intervene in good time should anomalous values be encountered.

By “signaling means” is generally intended any device able to signal, i.e. transmit to the users, a direct or indirect measurement of the temperature of the lubricating oil.

In a general sense, the signaling means could therefore be connected to a separate sensor able to perform the measurement of the temperature of the lubricating oil.

However, in a preferred embodiment of the present invention the signaling means include, as a thermometer, also the measuring means of the temperature.

By applying a thermometer to the casing an indirect measurement of the temperature of the lubricating oil is obtained, with a technically very simple and easily-applicable solution.

In a preferred aspect of the invention this thermometer can contain a thermochromic substance, which is able to change color on the basis of the temperature to which it is heated.

The thermometer can be for example a liquid crystal thermometer (LCT) which can be applied to the casing with an adhesive.

In a further aspect of the present invention, the pump can also comprise signaling means of the level of the lubricating oil contained in the internal volume of the casing.

This aspect of the invention is advantageous as the effectiveness of the lubrication system also depends on the fact that the level of the lubricating oil is comprised between a minimum design value and a maximum design value.

At present the level of the lubricating oil is controlled during periodical maintenance interventions of the high-pressure pump, for example by means of a graduated rod which is inserted into the casing through the filler mouth of the lubricating oil.

This control procedure is however rather awkward and laborious, and the users tend to leave too much time between checks of the level of the lubricating oil, with the consequence that the high-pressure pump can sometimes be functioning in non-optimal lubricating conditions, increasing wear and energy consumption.

Thanks to the above-mentioned signaling means applied to the casing, the users can keep the lubricating oil level under control in a very much simpler and more immediate way.

In this case too, by “signaling means” in generally meant any device able to signal, i.e. transmit to the users a direct or indirect measurement of the level of the lubricating oil internally of the pump casing.

An embodiment of the present invention includes for example the signaling means of the level simply comprising a transparent body which can enable a direct vision of the level of the oil contained in the internal volume of the casing.

In this way the users are able to control the level of the lubricating oil visually and rapidly, with a solution that is extremely simple and economical.

A further advantage of this solution consists in the fact that the users can directly view and therefore control also the color and/or opacity of the lubricating oil, for example in order to see whether the oil is excessively dirty or worn or whether it has been contaminated with infiltrations of water during the functioning of the pump.

In an aspect of this embodiment, the transparent body can be faced to the opaque contrast body (i.e. a non-transparent body), with which it defines a gap that is in hydraulic communication with the internal volume of the casing.

This solution has the advantage of improving the vision of the level and qualitative characteristics of the lubricating oil, as the contrast body can reflect a part of the external light, enabling a better illumination of the slim layer of lubricating oil which is in the gap between the contrast body and the transparent body.

In a preferred embodiment of the present invention, the signaling means of the temperature and/or the signaling means of the level can both be applied to a removable cover of the casing.

Thanks to this solution, the cover can be realized and assembled separately with respect to the casing, simply and economically, and be fixed to the casing later, during the step of assembling the high-pressure pump.

In an aspect of this embodiment, the cover can be aligned with the rotation axis of the crankshaft, for example it can be the cover which supports one of the support bearings for the crankshaft.

Thanks to this solution, the signaling means are in an optimum position for enabling the users to control the level and the temperature of the lubricating oil.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will emerge from a reading of the following description, provided by way of non-limiting example, with the aid of the figures illustrated in the accompanying tables of drawings.

FIG. 1 is a perspective view of a high-pressure piston pump in an embodiment of the present invention.

FIG. 2 is a lateral view of the pump of FIG. 1.

FIG. 3 is section III-III of FIG. 2.

FIG. 4 is a larger-scale detail of FIG. 1.

FIG. 5 is a larger-scale detail of FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As illustrated in FIG. 3, the high-pressure pump 100 can comprise a plurality of pistons 105 arranged in line and with parallel axes, each of which is slidably inserted internally of a respective cylinder (not visible) with which they define a pumping chamber.

The high-pressure pump cylinders 100 are realized internally of a head 110, which can be manufactured as a monolithic body made of a metal material, typically brass.

As illustrated in FIG. 2, also realized in the head 100 are an aspirating manifold 115 for the fluid to be pumped (for example water) and a delivery manifold 120 for the pressurized fluid, which are in communication with each of the pumping chambers respective through an aspirating valve and a delivery valve (not visible). The aspirating and delivery valves are singly housed internally of respective seating 125 and 130 (FIG. 1), which are fashioned in the head 110 and are sealedly closed by appropriate threaded caps 135 and 140.

The head 110 is fixed to a metal casing 145, for example steel or cast iron, internally of which a crankshaft 150 is rotatably housed, having a rotation axis perpendicular to the piston axes 105 (FIG. 3). This crankshaft 150 is profiled in such a way as to define a number of lengths of crankshaft that is equal to the number of pistons 105, and each of these lengths of crankshaft is connected to a respective piston 105 by means of a conrod 155 which is also contained internally of the casing 145. In this way, the rotation of the crankshaft 150 is transformed by each conrod 155 into an alternating motion of the respective piston 105, thus causing pumping of the fluid from the aspirating manifold 115 to the delivery manifold 120.

The crankshaft 150 is supported internally of the casing 145 by a pair of bearings 160 and 165, each of which is axially housed and blocked in a seating afforded in a respective metal cover 170 and 175. The covers 170 and 175 are fixed on opposite flanks of the casing 145, substantially aligned to one another and to the crankshaft 150. In particular, each cover 170 and 175 is fixed to the casing 145 by means of demountable fixing means, in the example by a series of screws 180, such as to be removable and separated from the casing 145 in case of need. The end of the crankshaft 150 located at the cover 170 terminates and is contained internally of the casing 145, while the opposite end projects externally of the cover 175, such as to define a connecting spur by means of which the crankshaft 150 can be connected with an activating motor, possibly through a suitable transmission and reduction system.

The internal volume of the casing 145 further contains a predetermined quantity of lubricating oil (not visible) which is destined to lubricate, by shaking circulation, the entire mechanism of the high-pressure pump 100 and in particular the bearings 160 and 165, the joints between the crankshaft 150 and the conrods 155, and the joints between the conrods 155 and the respective pistons 105. This lubricating oil can be poured internally of the casing 145 by means of an inlet mouth 185 (see FIG. 1) and can possibly be discharged via an outlet mouth 190 (FIG. 2), both of which are normally closed by a respective removable closing cap.

As illustrated in FIGS. 4 and 5, the cover 170 exhibits a projecting portion 195 having a generally cylindrical shape, which is aligned and substantially coaxial with the crankshaft 150. This projecting portion 195 terminates with an end wall 200 that is substantially flat, to which are associated both a device 205 for signaling the level of the lubricating oil internal of the casing 145 and a thermometer 210 able to measure and signal the temperature of the lubricating oil.

The thermometer 210 can be one containing a thermochromic substance, which changes color on the basis of the temperatures to which it is heated. For example, the thermometer 210 illustrated in the figures is a liquid crystal adhesive thermometer, which is fixed on the bottom of a lowering 215 having a substantially semicircular shape which occupies about a half of the external surface of the end wall 200. In this way, the thermometer 210 measures the temperature of the cover 170, which however represents an indirect measurement of the temperature of the lubricating oil.

A liquid crystal thermometer can generally comprise two layers of flexible and impermeable material, of which a lower layer applicable on the surfaces the temperatures of which are to be measured, and an upper layer that is at least partially transparent. These two layers are reciprocally superposed and fixed such that between them a plurality of separate and sealed compartments is defined, each of which contains a mixture of liquid crystals. This mixture of liquid crystals has the property of having a substantially black coloring, apart from when the temperature is comprised within a predetermined interval of values, in which case the liquid crystals are arranged such as to reflect/refract the light and illuminate the relative compartment. By using mixtures of liquid crystals that are different for each compartment is it therefore possible to make it so that they illuminate alternatively, each for a different temperature interval, enabling the thermometer to signal the temperature at present reached.

In the illustrated embodiment, the thermometer 210 comprises for example a lower compartment 220 which is configured such as to illuminate, with a blue color, up to a temperature of about 45° C., an intermediate compartment 225 able to illuminate with a green color for a temperature comprised between about 45° C. and 85° C., and an upper compartment 230 able to illuminate with a red color for a temperature of above 85° C. In this way, the illumination of the lower compartment 20 can signify that the lubricating oil is too cold to guarantee an optimal lubrication; the illumination of the intermediate compartment 225 can signify that the lubricating oil has reached an optimum value; while the illumination of the upper compartment 230 can signify that the lubricating oil is too hot and a dangerous condition has been reached.

Returning to the cover 170, the device 205 for signaling the level of the lubricating the oil comprises a substantially semi-circular opening 235, which occupies about the remaining half of the external surface of the end wall 200. This opening 235 opens internally of a rear-lying cylindrical cavity 240 of the cover 170, which is arranged coaxially with the crankshaft 150 and is in communication with the internal volume 145 of the casing 145 (see FIG. 5). A disc 245 made of a transparent material, for example plastic or glass, is snugly housed internally of the cylindrical cavity 240, and defines therewith a window through which the inside of the casing 145 can be viewed. To prevent undesired leakage of lubricating oil from the opening 235, a suitable annular seal 250 is interposed between the transparent disc 245 and the cylindrical cavity 240. An opaque (i.e. not transparent) contrast disc 255 is also housed internally of the cylindrical cavity 240, which disc 255 is interposed between the bearing 160 and the transparent disc 245 in such a way as to define therewith a narrow gap 260. The contrast disc 255 exhibits through-holes 265, by means of which the gap 260 is in hydraulic communication with the internal volume of the casing 145.

In this way, the lubricating oil is arranged internally of the gap 260 at the same level as internally of the casing 145, enabling a user to see the level directly through the portion of the transparent disc 245 that closes the opening 235. The viewing of the level of the lubricating oil is facilitated by the contrast disc 255 which, reflecting at least in part the external light, is able to illuminate the slim layer of oil which occupies the gap 260. At the opening 235 a graduated scale (or the equivalent) might be present such as to indicate the predetermined levels for comparison with the actual level of the lubricating oil.

Thanks to this viewing system, a user is also advantageously able to see and therefore directly control also the color and/or opacity of the lubricating oil, for example in order to evaluate whether it is excessively dirty or exhausted or whether it has been contaminated with water infiltrations during the functioning of the pump.

Obviously a technical expert in the sector might make numerous modifications of a technical nature to the high-pressure pump described in the foregoing without forsaking the scope of the invention as claimed in the following. 

1. A pump (100) comprising a head (110), in which at least a cylinder is fashioned in which a piston (105) is slidably housed, and a casing (145) fixed to the head (110), which defines an internal volume in which a crankshaft (150) and at least a conrod (155) are housed, said at least a conrod (155) connects the crankshaft (150) with the piston (105), such as to be able to transform a rotary motion of the crankshaft (150) into an alternating motion of the piston (105), wherein signaling means (210) of the temperature of lubricating oil contained in the internal volume of the casing (145) are applied to the casing (145).
 2. The pump (100) of claim 1, wherein the signaling means (210) further include measuring means of the temperature.
 3. The pump (100) of claim 2, wherein the measuring and signaling means (210) comprise a thermochromic substance.
 4. The pump (100) of claim 3, wherein measuring and signaling means (210) are a liquid crystal thermometer.
 5. The pump (100) of claim 4, wherein the liquid crystal thermometer is applied to the casing (145) by means of an adhesive.
 6. The pump (100) of claim 1, further comprising signaling means (205) of the level of the lubricating oil contained in the internal volume of the casing (145).
 7. The pump (100) of claim 6, wherein the level signaling means (205) comprise a transparent body (245) which enable a direct viewing of the level of the oil contained in the internal volume of the casing (145).
 8. The pump (100) of claim 7, wherein the transparent body (245) faces an opaque contrast body (255), with which it defines a gap (260) which is in hydraulic communication with the internal volume of the casing (145).
 9. The pump (100) of claim 6, wherein the signaling means (210) of the temperature of the lubricant oil and/or the level signaling means (205) are applied to a removable cover (170) of the casing (145).
 10. The pump (100) of claim 9, wherein the cover (170) is aligned with the rotation axis of the crankshaft (150). 